1. Field of the Invention
This invention relates to the use of a certain multi-phase, thermoplastic elastomeric polymer for damping purposes, and new damping compositions comprising said polymer.
2. Description of the Prior Art
Lorentz et al., pps. 306-329, in Piirma and Gardon, ed., "Emulsion Polymerization", American Chemical Society Symposium Series 24, Washington, DC, 1976, and Sperling, pps. 21-56, Paul and Sperling, ed., "Multicomponent Polymeric Materials", American Chemical Society Symposium Series 211, Washington, D.C., 1986, have discussed in detail the damping properties of two-phase emulsion polymers of varying composition wherein the second polymer is polymerized in the presence of the first.
Lohr, U.S. Pat. No. 3,430,902 teaches a vibration damping device comprising a solid, high molecular weight amorphous polymer utilized at or near its glass temperature combined with means for heating or cooling so that the glass temperature is approximately that of the use temperature of the vibration support.
Tabar et al. U.S. Pat. No. 4,362,840 and U.S. Pat. No. 4,419,480; Lemieux et al., Rubber Chem. Tech., 57, 792 (1984); Mazich et al. ibid., 59, 623 (1986) teach soft compositions useful as low modulus, high damping, high fatigue life elastomer compounds for vibration isolation. The compounds are cured, vulcanized, or crosslinked blends of natural rubber with bromobutyl rubber to which has been added a non-vulcanizable polyisobutylene which remains in a discrete phase after cure; a particulate additive such as carbon black is also incorporated. These two patents also teach the use of synthetic poly(isoprene) or polybutadiene in similar blends to improve the heat resistance of the blend.
Falk et al, U.S. Pat. No. 4,473,679, claim thermoplastic core-shell compositions having a rigid core surrounded by a rubbery acrylic partially encapsulating layer, with a copolymeric transition layer formed from the mixture of monomers used to prepare the core and shell layer.
Makati et al, U.S. Pat. No. 4,717,750 and U.S. Pat. No. 4,742,108; Lee et al., U.S. Pat. No. 4,569,964 teach reinforced latex particle structures. The Makati et al. patents teach a second phase of glass temperature higher than either the first or third phase.
Hofmann, U.S. Pat. No. 4,180,529, teaches a four-phased emulsion polymer having a non-elastomeric second phase which may contain up to 5% of a crosslinking monomer in combination with a elastomeric first phase. Owens, U.S. Pat. No. 3,793,402 teaches a similar staging with an additional thermoplastic outer phase.
The Derwent abstract of Japanese Patent 79-8497 teaches blends of liquid thermosetting resins with rubbery polymers and linear thermoplastic resins as vibration-reducing materials useful at high temperatures and flexible at ordinary temperature.
The Derwent abstract of Japanese Patent 88-1979 teaches blends of natural rubber with a soluble chloromethylstyrene-butadiene-styrene terpolymer as a useful high modulus elastomeric product.
Frankel et al. European Patent Application 187,505, published July 16, 1986, teach two-phase polymers used in the present invention.
Sugii et al. (Nitto Electric) in Japanese Kokai 60-92372 teach a polymer useful as an improved pressure sensitive adhesive by first polymerizing a (meth)acrylic polymer which produces a tacky material, adding a monomer mixture enriched in a multifunctional monomer, along with an organic peroxide, to swell the particles and conducting the polymerization of the second monomers at an elevated temperature.